1. Field of the Invention
This invention relates to a method of constructing swimming pools wherein the pool wall surface of a previously assembled swimming pool is covered with a layer of foamable plastic material.
2. Description of the Prior Art
The utilization of polyurethane foam to form a swimming pool using the earth as a form is not new. The U.S. Pat. No. 3,429,085, to Stillman, shows a swimming pool in which the bottom and sides of the excavated ground provide a form for the application of a plurality of layers of foam in a first less dense foam and then in a second more dense layer with an interior cover liner such as a vinyl liner placed thereon.
No method of constructing a swimming pool utilizing previously assembled pool walls to which foam is applied is even contemplated in Stillman.
The U.S. Pat. No. 2,903,380 to Hoppe describes a process for producing composite structures comprising rigid polyurethane foams and covering layers. The patent describes the process of covering the material to which the foam is to be applied with a preliminary covering of a polyesterisocyanate mixture to which the foam bonds. No swimming pool is shown or suggested in Hoppe.
The U.S. Pat. No. 3,698,927 to Sawyer describes a foam structure with a protective overcoat. In this patent the material can be formed in place as a roofing cover wherein the building acts as a form for the foam structure.
No swimming pool is shown or suggested in the Sawyer patent.
The U.S. Pat. No. 3,841,041 to Friedland et al. describes a swimming pool formed in the ground of a rigid, plastic material such as polyurethane foam, the modulus of elasticity of the side walls being close in value to the surrounding soil to provide uniform stress distribution and avoidance of crack formation. A fluid tight lining is applied to the foam and a few pins may be anchored in the foam and the ground. No swimming pool wherein the structure to which the foam is to be applied is a previously assembled pool is contemplated in Friedland et al.
Many of the prior art patents disclose structures wherein the ground provides a form for the pool to be built and in which the foam is directly engaged therewith determining the slope of the pool but none discloses the foam application to a previously assembled pool.
It is desirable to provide swimming pools of low cost with high integrity against water leakage and with side walls that are not likely to deform. The use of swimming pools with a lower channel into which interlocking aluminum boards are placed with an upper channel carrying a removable vinyl liner has become increasingly popular. The vinyl liners used with such pools are restricted in shape and do not have as long a service life as is desired. Such vinyl liners are difficult to remove for repair or replacement and the fact that they must be capable of removal restricts the type of coping that can be utilized thereon.
Another type of pool in use is constructed of heavy gauge aluminum plates welded together along each intersecting edge to form continuous walls. It is very difficult to weld aluminum, the heat involved and the size of the plates being such that it is almost impossible to prevent warpage and obtain a satisfactory finished surface, and such welds are often subject to leakage due to inclusion of air pockets. The welds must be ground and the surface of the plates treated with acid prior to painting which is a difficult and dangerous process. In climates where the ground temperature is lower than the pool water temperature, the high thermal conductivity of aluminum results in a lowering of pool water temperature. In climates where the surrounding ground temperature is high then the water in the pool may reach an unacceptable level. The result is that optimum water temperature in all aluminum pools is difficult and expensive to maintain.
No satisfactory paint has been developed which will bond well to and provide any degree of permanence when used on aluminum pools.
My invention provides an economical method of constructing swimming pools of aluminum boards or sheets which in addition to providing a finished surface for painting improves the safety and appearance of the pool while aiding in maintaining the water at a more even temperature.